Separation of schoenite by flotation



United States Patent 3,456,791 SEPARATION OF SCHOENITE BY FLOTATION Jose L. Ramirez, Agro-Quimicas de Honduras, Apartado Postal 362, Tegucigalpa, Honduras No Drawing. Filed Apr. 17, 1967, Ser. No. 631,180 Int. Cl. B03d 1/02 U.S. Cl. 209166 5 Claims ABSTRACT OF THE DISCLOSURE A froth flotation process for separating schoenite from salt mixtures containing schoenite in admixture with other salts, such as sodium chloride, magnesium sulfate hydrates and kainite, in which the flotation agent is a collector in the form of a water-soluble petroleum sulfonate having a molecular weight between 300 and 400.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to the concentration and separation of schoenite from salt mixtures containing sodium chloride, epsomite and other impurities in the medium of an aqueous brine by froth flotation to obtain schoenite concentrates of high purity and with high yields from the raw salt mixtures.

Description of the prior art The separation of schoenite (commonly represented as K SO -MgSO -6H O) from salt, epsomite and other impurities by flotation procedures has heretofore been disclosed, as shown, for instance, in German Patent No. 945,622; Italian Patent No. 573,975; and in J. Applied Chem. (USSR), 12, 836 (1939), various flotation agents having been suggested including alkyl sulfates, saturated and unsaturated fatty acids, naphthenic acid, and sulfonaphthenic acid. Generally, these agents require, for their reasonably effective use, the addition of various dispersants and frothers.

SUMMARY OF THE INVENTION My invention provides a simpler and less costly separation procedure utilizing certain petroleum sulfonates, gen erally without the need for dispersants and frothers. Sulfonated petroleum oils with a molecular weight of from 300 to 400, and which are water-soluble, and are used in the form of their water-soluble salts, notably their sodium salts, have been found to be very effective. A typical flotation agent consists, in commercial form, of the order of 30% petroleum sulfonates, 50% water, 10% mineral oil and 10% inorganic salts. The flotation agent may, of course, be used in a more purified, active form but this is unnecesary. While the invention is particularly useful in processing schoenite produced by the conversion of kainite to schoenite, it is also applicable to any salt mixture containing schoenite and one or more of kainite (commonly represented as KCl-MgSO -2.75H O), sodium chloride, epsomite (commonly represented as and other impurities. My invention will be described below in connection with schoenite obtained from the conversion of kainite, but it will be understood that it is not limited thereto.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the practice of my invention, generally speaking, a raw salt mixture, which typically may contain of the order of schoenite, 50% sodium chloride, 12% epsomite, 12% kainite, and including minor amounts of 3,456,791 Patented July 22, 1969 other impurities, is slurried with a kainite-schoenite conversion end liquor, typically containing of the order of 8% sodium chloride, 4% potassium chloride, 8 magnesium chloride, 11% magnesium sulfate, and the balance water. The slurry which is conditioned with the petroleum sulfonate flotation agent, and which may -be diluted with additional kainite-schoenite conversion end liquor, is then treated in a flotation cell. When air is introduced to the flotation cell, a froth containing mainly schoenite is formed and removed from the cell.

Contrary to many other procedures, only the aforesaid petroleum sulfonate flotation agent is added to the slurry, and, although frothers and depressants may be used, they are generally not necessary. Frequently, the presence of clay or other fine particles in the raw salts makes eflective flotation very diflicult. With the petroleum sulfonate flotation agent, a schoenite float of good purity may be obtained even in the presence of appreciable amounts of clay.

The application of my invention may be further understood by the following illustrative examples. All percentages recited are by weight.

Example 1 TABLE].

Analysis, percent K Na lug Cl S04 1120 ffiiiififll-ITJJIIII: i233 591? iii? i338 3:33 iii A sulfonated petroleum oil flotation agent, in this example Petroflote 130, (Witco Chemical Company) and containing about 30% water-soluble petroleum sulfonates, with molecular weight between about 350 and 370, together with 50% water, 10% mineral oil and 10% inorganic salts was added in the proportion of 600 grams of agent per metric ton of solid feed, and the slurry with re agent was conditioned for about 5 minutes. The slurry was diluted to 25% solids by the addition of kainite-schoenite conversion liquor, and placed in a flotation cell. When air was introduced into the agitated flotation cell, a froth containing schoenite formed at the top of the cell. This float was removed and weighed, and the residue salts were also removed. Compositions of the float and residue are shown in Table II.

TAB LE II Analysis, percent K N 2. Mg C1 S04 E20 Float 16. 51 2. 41 5. 33 5. 27 39. 86 30. 52 Residue 1. 47 34. 09 0. 64 53. 54 3. 13 7. 13

The float, weighing 239 grams, containing about 92% schoenite and 7.3% sodium cholride, represented a yield of about 86% of the schoenite in the feed salts.

Example 2 3 the flotation cell, a froth containing schoenite was formed and removed from the cell. Compositions of the float and residue are shown in Table III.

The float, Weighing 149 grains, contained about 97% schoenite and 2.8% sodium chloride, and represented a yield of about 53% of the schoenite in the feed salts.

Example 3 The yield from the flotation may be increased by refloating the residue salts, Without additional reagent consumption. Feed salts identical to those of Example 1 were ground to -32 mesh and conditioned for about 5 minutes as a 50% slurry in kainite-schoenite conversion liquor with 400 grams of petroleum sulfonate reagent per metric ton of solids. The slurry was diluted to 25% solids with kainite-schoenite conversion liquor and placed in a flotation cell. The froth produced when air was introduced to the cell Was removed, and the residue was also removed and reconditioned for 20 minutes with an additional 200 grams of petroleum sulfonate reagent per metric ton of solids.

The residue was refloated, and another schoenite froth obtained. The compositions of the two floats and the residue are shown in Table IV.

TABLE IV Analysis, percent K Na Mg ()1 S04 E20 First float 1. 56 5. 65 2. 99 40. 76 31. 87 Second float- 2. 38 5. 08 6. 06 34. 41 37. 07 Residue 1. 83 31. 35 1. 04 49. 83 7. 59 8. 36

The reagent consumption of 600 grams per metric ton of feed solids was the same as in previous examples.

I claim:

1. A process for separating schoenite from salt mixtures containing schoenite and one or more of sodium chloride, epsornite and other magnesium sulfate hydrates, kainite and other impurities which comprises subjecting said mixture, in the form of an aqueous slurry, to a froth flotation separation with a collector comprising a water-soluble petroleum sulfonate having a molecular weight between 300 and 400, whereby to float olf a schoenite concentrate.

2. A process according to claim 1, wherein the petroleum sulfonate collector is used in the form of a composition containing of the order of at least of said sulfonate, not more than Water, and minor amounts of mineral oils and inorganic salts.

3. A process according to claim 1, wherein the salt mixture is composed of salts containing schoenite and an aqueous brine which is essentially saturated with the water soluble components of the salt mixture.

4. A process according to claim 1, wherein the mixture of salts is composed of salts from the conversion of kainite to schoenite, or kainite mixed with other salts, and an aqueous liquor obtained from the kainite to schoenite conversion process.

5. A process according to claim 1, wherein the residue from a first flotation is conditioned with additional collector agent and rcfloated to obtain an increased yield of schoenite.

References Cited UNITED STATES PATENTS 1,765,308 6/1930 Lutz 209-166 2,442,455 6/1948 Booty 209-166 2,596,407 5/1952 Jackson 209166 X 3,164,549 1/1965 Seymour 209166 FOREIGN PATENTS 574,442 3/ 1958 Italy.

HARRY B. THORNTON, Primary Examiner ROBERT HADPER, Assistant Examiner US. Cl. X.R. 252-61 

